When I try to mount an ntfs partition on my hard-drive (via Thunar), it prompts me for root password, and in details is shows me that action is "org.freedesktop.udisks.filesystem-mount-system-internal" and vendor "The udisks Project".

That dialogue does not appears when I mount the external usb flash stick, everything goes ok, and no password is required.

I have defined all required action (as I think) for mounting without problems, i.e.

** Note: the following localauthority stuff is obsolete and is no longer used by polkit (see ssuominen's post) **

You could also do it the Arch way by letting users in the group "storage" mount without password by using a local authority file. Create a '/etc/polkit-1/localauthority/50-local.d/50-filesystem-mount-system-internal.pkla' with these contents:

You could also do it the Arch way by letting users in the group "storage" mount without password by using a local authority file. Create a '/etc/polkit-1/localauthority/50-local.d/50-filesystem-mount-system-internal.pkla' with these contents:

You could also do it the Arch way by letting users in the group "storage" mount without password by using a local authority file. Create a '/etc/polkit-1/localauthority/50-local.d/50-filesystem-mount-system-internal.pkla' with these contents:

XML .pkla files are no longer used at all, there should only be JS .rules files in /etc/polkit-1/rules.d/
You can safely rm -f *.pkla, and even entire localauthority/ subdir

Ah of course, thanks! Explains why anything pklocalauthority related is no where to be found on the system now (and why it didn't do a thing in my tests :/). If I get around to it, I'll update the ArchWiki page.